14. Lactic acid (HC3H5O3)
is a weak organic acid found in milk and in muscle tissues during strenuous
exercise. determine the pH of a solution that contains 25.0 g of lactic
acid and 38.0 g of potassium lactate in 500.0 mL of solution (Ka for
lactic acid is 1.38 x 10-4).

15. Potassium acid oxalate (a solid acid) can
be described as the acid salt formed by the partial neutralization of the
diprotic acid, oxalic acid. A student dissolved 0.60 g of KHC2O4
in 55.0 mL of water and determined that 46.2 mL of 0.10 M NaOH was required
to reach the endpoint of the titration. Determine the molecular mass of
the solid acid. Calculate the student's percent error.

16. In murder-mystery movies, cyanide is introduced
into the victim's body in the form of a harmless looking salt, potassium
cyanide, a deadly poison. Calculate the pH of a 0.0010 M solution of potassium
cyanide. (Ka for HCN = 4.9 x 10-10.